Hydraulic shock absorber



July 5, 19.38. H. L cHlsl-loLM. JR

lHYDRAULIC SHOCK ABSORBER Il f f Filed March 15, 1937 Patented July s,193sv HYDRAULIC SHOCK ABSORBER Harry L. Chisholm, Jr., Buffalo, N. Y.,assit/nor to Houde Engineering Corporation, Buffalo, N. Y., acorporation of New York Application March 15, 1937, Serial No. 130,851

Claims. (Cl. 18S-88)' This invention relates to. hydraulicV shockabsorbers, and more particularly -to those of the direct acting typeadapted for'use on automotive vehicles for modifying the action of thevehicle springs.

An important object of the invention is to provide an improved valvingarrangement for controlling the ow of the displaced fluid for thedesired shock absorbing action of the shock absorber.

A further object is to provide adjustable valve means entirely concealedwithin the shock" absorber structure after assembly thereof, and meansalso entirely within the shock absorber structure. cooperable with thevalve means for adjustment thereof upon relative rotational movement" ofthe cylinder and piston elements after movement of suchelements to apredetermined relative position.

The various features of my inventionare incorporated in the structureshown in the drawing, in

' which drawing:

Figure 1 is a vertical diametrical section of the shock absorber; l y

Figure 2 isa section on plane II-II of Figure 1;

Figure 3 is an enlarged side elevation of the valve members;

Figure 4 is a plan view of the valve adjusting members; and l Figure 5is a view similar to Figure 1 showing a modified arrangement.

The structure shown 'comprises a cylinder I0 having the boss I Iextending longitudinally at one side thereof to provide a fluidreservoir I2. The cylinder and the boss may be part of an integralcasting. At its lower end, .the cylinder is closed by a plug I3 havingdetachable threaded engagement with the cylinder end, a gasket I4 beingpreferably interposed to seal against leakage. At

, its upper end the cylinder is closed by a headeror plug I5 havingdetachable threaded connection with the cylinder, the plug having a boreI6 for reception of a bearing bushing I1 for the piston rod I8,.which atits inner end carries the piston structure.

45 The piston structure comprises the piston head I9 having the guideskirt 20. ceives the inner end of the piston rod, which is threaded forreception of a nut 2| for clamping the head to the rod, a gasket 2'I'being preferably 50 interposed. l

rExtending through the piston head are ports 22 for flow of-hydraulicfluid from one side of the piston to the. other, the dow through theseports beingcontrolled by a valve 23 in the form of an u annular plate ordisk above the piston head. The

The piston head revalve is vertically reciprocable, and is guided by theneck 24 at the upper end vof the piston head, its

upward movement being limited by its engagement with an abutment plate25 clamped between the neck 24 and the piston rod. During instroke 5 ofthe piston, the valve 23 will be raised from its seat by the fluidpressure so that the fluid may flow freely through the ports 22. Uponupward movement of the piston',y the pressure applies the valve over theports to prevent fluid flow there- 10 through. ,I

At its inner end, the piston rod has the bore 26, which is connectedwith the cylinder above the piston by radial ports 2l. The connection ofthe bore with the cylinder below the piston is con- 15 trolled by avalve V. The valve shown is in the form of a cylindrical cup 28 threadedon its outside for engagement with the internal threading at the lowerend of the bore 2B. The valve has longitudinally extending slits 29which cooperate with 20 'Y the lower edge 3G of the piston rod to definerestricted orifices 3i for controlling the fluid flow from one side ofthe piston to the other. The size of the orices may be adjusted byrotational movement of the valve, which, on account of the 25 threading,will result -in axial movement of the valve for increasing or decreasingthe size of the orifices. As shown in Figure 3; the valve, after beingslitted, is expanded slightly radially in order that, when inserted intothe end of the piston rod 30 bore 26, it will have clamping engagementfor frictionally holding it securely in adjusted position.

At its upper end the bore I2, which forms a reservoir, may be closed asby a sealing plate 32. At its lower end, the bore isclosed by aremovable 35 plug 33 through which end the hydraulic fluid may be pouredinto the reservoir and into the cylinder. A distance above the lower endof the reservoir bore is a partition 34, which may be in the form of aplug threaded into the lower threaded end of the bore. This partitionhas the two passageways 35 and 3S, the ow through the passageway 35being controlled by a restricted orifice 31 in the base ofa thimble 38inserted in the lower end of the passageway. The flow through thepassageway 36 is controlled by a check valve which may i be in the formof a ball 39, the arrangement being such that the ball will preventupward flow through the passageway, but will permit free downward flowtherethrough. Below the partition 34 the reservoir is connected with thelower end of the cylinder by a passageway 4U.

The closure plug I4 for the cylinder terminates in an eye 4I, by whichthe lower end of the cylinder may be connected with a support, as forexam- :Springs A ple the axle of an automotive vehicle with'V thesprings of which the shock absorber ls to be associated. Secured to theouter end f the piston rod I6, as by threading, is a tting 42 having theeye 43 by means ofwhich the piston rod may be connected with a support,as for Yexample the chassis of the vehicle. When the shock absorber isapplied to the vehicle, the cylinder and piston eletnents will have onlyrelative longitudinal movement duringrcperation .of the vehicle, andwill be held against relativerrotational movement.

During compression motement of the vehicle springs, the pistonstructurewill move inwardly, part of the fluid displaced from the inner end ofthe cylinder flowing to the upper end of the cylinder through ,the ports22, the fluid pressure having lifted the valve 23 to expose the*Y ports.Owing to the volumetric differential between the working chambers of thecylinder-on account of the volume of the piston rod, the outer chambercannot accommodate all of the fluid displaced from the inner chamber,and the'surplus fluid will therefore flow through the passageway 40 intothe lower end of the reservoir bore I2 and into the reservoiry spacethrough the orifice 31 in passageway 35, the passageway 36 being then'closed bythe ball 39. The orifice 31 will meter the flow of the surplusfluid and will produce the required hydraulic flow for shock. absorbingresistance during the compression movement of the vehicle springs.

' During rebound movement of the vehicle I d outward movement of thepiston in the cylinder, the valve 23 will be shifted to close the ports22, and then the only outlet from the outer end of the cylinder to theinner end theree of will be by way of the piston rod boreY 26 and i therestricted orices 3|, which orifices will meter 'the flow for productionof the desired shock absorber resistance to spring rebound. Due to thevolumetric differential f between the cylinder chambers, outwardmovement of the piston` will tend to ereate vacuum or suction in theinner end of the cylinder, but this vacuum is broken by the free flow offluid from the reservoir through the passageway 36 and the passageway40,-'into the inner end of the cylinder.

At its outer end, the closure plug I5 for the outer end of the cylinderhas the recess 44 for suitable packing material 45 surrounding the pis.-ton rod to prevent escape to the exterior of the shoclg absorberV of anyfluid which may have leaked past the bushing l1. Any such leakage fluidwill be returned to the upper end ct the reservoir through the passage46 extendingrfrom the bottom of the recess 44. A sheet metal cylindricalshell or shield 41 may be suspended from the fitting 42 to surround thecylinder end reservoir structure.

Before the shock absorber is assembled, the valve J is adjusted asclosely as possible for the desire-d service. However, it may bedesirable to effect la final adjustment after the shock absorber hasbeen assembled and before it is applied to the vehicle. I thereforeprovide an arrangement whereby such adjustment may be accomplished by.relative rotational movement of the cylinder and piston. In the bottomof the bore of the closure plug I 3, a disk or plate 48 is rigidlyseated, this plate having an elongated diametrically extending slot 49.The valve V has a lug or tongue 50 extending Yfrom its base andextending diametrcally and elongated to engage the slot 49 of the plate48. To make the adjustment, the piston rod is pushed inwardly to shiftthepiston to the innermost end of the cylinder. After such relativeVlongitudinal setting of the cylinder and piston, a relative turningthereof in one direction or the otherjwill rotate the threaded valve Vso that by resulting axial movement the size of the orifices 3| may becorrespondingly increased or Idecreased for the desired hydraulic actionduring Y rebound movement of the vehicle springs. After the shockabsorber is secured in service position: on the vehicle and the cylinderand piston held against relative rotational movement, the adjustmentsetting of the valve will be maintained duringsubsequent serviceoperation Yof the shock absorber. if

In the modified arrangement shown in ligurf',

closed at its lower end by a header plug'52. The reservoir space 53 isprovided betweenthe tubeVY 5| and an outer tube 5e coaxial'with the tube5l and secured atV its lower end to the tting'55, which terminates inthe eye 56, the cylinder header 52 seatingagainst the fitting 55. 'Ihepiston structure and valve means for controlling the flow ofhydraulic'fluid from one side to the other thereof is the same as thatshown in Figure 1,and the same reference characters are thereforeapplied thereto.

The cylinder header 52 has the frusta-conical recess or (cavity 51 fromwhich passageways 58 and 59 lead to the lower end of the reservoir space53. 'I'he flow through the passageway 58 is controlled by an orifice 6Uin the oase of a thimhle 6I seated in the inner end of the passageway58. The flow through the passageway 59 is controlled by a check valvesuch as a ball 62 which closes the passageway, against flow into thereservoir but permits free reverse flow. During inward movement of thepiston in the cylinder, the displaced fiuid flow which cannot beaccommodated by the ports 22 in the piston will be through the orifice60 and-into the reservoir. During outward valve V when the piston ismoved to the innermost position in the cylinder, so that when thecylinder and piston are then relatively rotated the valve V may beadjusted.

For supplying the shock absorber with hydraulic'fluid, the tting 55 m'ayhave the diagonally extending filling passageway 65 which communicateswith the slot 64 in the plate 63, the outer end of the ller passagebeing closable by a threaded plug 66. The chargedfin fluid will flowthrough the slot 64 into the cylinder and through the passages 58 and 59into the reservoir. A shield tube 61 is preferably provided around theshock absorberstructure, and this shield tube may be suspendedfrom afitting at the upper end of the piston rod in a manner as shown inFigure 1, or in'any other suitable manner.

I have thus produced a simple, compact, and efcient shock absorberstructure of the direct acting type in which accurate adjustment andsetting of the rebound flow controlling valve may be readily effected byrelative rotation of the cylinder and piston after assembly thereof, sothat,

when the shock absorber is in service, the valve 75 1. In a hydraulicshock absorber of the direct acting type, a cylinder structure, a pistonstructure comprising a piston and a piston rod extending therefromthrough an end of the cylinder structureLsaid pistonV rod having a borein its inner end, a passageway including said bore for the ow of iiuidfrom one side of the piston `to the other during relative longitudinalmovement of said structures, a valve threading into the end of said boreand having a slit for cooperating with the end of the piston rod todeiine a restricted orice .for metering the ow through said passageway,and means within and carried by" the cylinder structure for cooperationwith said valve upon relative rotation of said structures for rotatingsaid valve for increasing or decreasing the size of said orice forsubsequent normal operation of the shock absorber.1

2. In a hydraulic shock absorber of the direct acting type, a cylinderstructure, a piston structure comprising a piston and a piston rodextending therefrom through an end of the cylinder structure, saidpiston rod having a bore at its cooperable with'the outer edge of saidbore to deline arestricted orice for metering the ow through saidpaageway, and means Within said,

cylinder structure effective upon relative rotational movement of saidstructures to rotate said valve for axial movement thereof to increaseor decrease the overlap of said port by said edge for determining thecontrol of the iiow by said orifice during subsequent normal operationof the shock absorber.

3. In a hydraulic shock absorber of the direct acting type, a cylinderstructure, a piston rod structure comprising a piston and a piston 'rodextending therefrom through an lend of the cylinder structure, saidpiston rod havingra bore extending therein from the inner end thereof,

Y the piston rod wall surrounding the entrance end operating with saidedge to detlne a restricted orifice for metering the ow through saidbore from one side of the piston to the other, and means eiiective whenthe piston is moved to its innermost position in said cylinder forconnecting said valve and cylinder for rotational movement of the valveduring relative rotational movement of said structures whereby saidvalve may be moved in axial direction for increasing or decreasing theoverlap of said port by said edge and .corresponding change in the sizeof the orice for control of the uid ow during subsequent normaloperation of the shock absorber.

A4. In a hydraulic shock absorber of the direct acting type, a cylinderstructure, a piston structure comprising a piston and a piston rodextending therefrom through an end oi the cylinder structure, saidpiston rod having a longitudinally extending passageway at its inner endfor flow of hydraulic iiuid from one side of the piston to the otherduring relative longitudinal movement of said structures, a valve havingthreaded engagement in the inner end of said passageway and having aport for cooperating with the endof the piston rod to deiine arestricted oriilce for meterx ing the iluid ow through said passageway,abutments on said valve and the inner` end of said cylinder,respectively, said abutments remaining out of engagement during normaloperation oi the shock absorber but being brought into engagement whenthe pistonds moved to its innermost position in the cylinder and beingthen effective upon relative rotational movement of said structures tocause rotary movement of said valve and thereby axial movement thereoffor increasing or decreasing the exposure of the valve port to saidpassageway for control of the fluid ow"durlng subsequent normaloperationwof the shock absorber.

5. In a hydraulic shock absorber of the direct acting type, a cylinderstructure, a piston struc,`

ture comprising a piston and a piston rod extending therefrom through anend of the cylinder structure, said piston rod having a passagewaytherethrough for flow of fluid from one side of the piston to the otherduring normal relative longitudinal movementof said structures, a valvehaving threaded engagement in said passageway and having a port for moreor less exposure to said passageway by the axial movement of said valve,a tongue on the end of said valve, means providing a slot at the innerend oi the cylinder for receiving said tongue when the piston is movedto its innermost position, the connection of said ltongue and slot beingeffective upon relative rotation of said 4structures to rotate saidvalve for aidal shift thereof for increase or decrease of the exposureof the valve port to said passageway and the desired shock absorbingaction during subsequent normal operation of the shock absorber.

HARRY L. CHISHOLM, Jn.

